Semiahmoo Exterior We get asked about LP SmartSide more than almost any other product. It's marketed well, it's usually cheaper than fiber cement, and plenty of homeowners in Whatcom County have it on their homes right now without obvious problems. So we want to be upfront about something: this isn't a scare piece. LP SmartSide is a legitimate engineered wood product, and it has genuine strengths. But it's also not what we put on the homes we work on, and we think you deserve a straight answer about why — especially if you live somewhere like Semiahmoo, where salt air, driving rain, and a moss season that can stretch half the year put real pressure on any exterior material.
What LP SmartSide Actually Is
LP SmartSide is engineered wood siding — strand board made from wood fibers, resin, and wax, pressed under heat and treated with a zinc borate additive for insect and fungal resistance, then coated with a primer or factory finish. It's a step up from old OSB-style siding failures of the 1990s, and LP has spent real engineering effort making it more moisture-tolerant than its predecessors. It comes in lap boards, panels, and trim, and it's genuinely easier and faster to install than fiber cement in a lot of cases — it's lighter, cuts cleaner, and doesn't require the same blade and dust-control precautions.
For a lot of markets — drier climates, inland regions, homes with generous roof overhangs — LP SmartSide performs reasonably well when installed correctly. We're not disputing that. Our concern is narrower and more specific to where we work.
The Core Issue: It's Still Wood at the Core
Strip away the resin and zinc borate treatment, and the core material is wood fiber. Wood fiber swells when it takes on moisture and shrinks when it dries out. Every layer of protection LP builds in — the resin binder, the treatment, the factory coating — exists to keep water away from that core, because once water gets past the surface and into the substrate, the failure mode is the same one wood siding has always had: swelling, softening, and eventual rot at the places where water lingers longest.
Those places are predictable: butt joints between boards, the bottom edges of lap siding, any cut edge that wasn't re-sealed in the field, and anywhere caulking has shrunk or cracked. In a dry climate, a small lapse in maintenance might go unnoticed for years. In Whatcom County, with our wet winters and the salt-laden air coming off Semiahmoo Bay and the Strait of Georgia, that same lapse gets tested constantly.
Why Our Climate Is a Harder Test
- Driving rain: Wind-driven rain off the water pushes moisture sideways into joints and seams, not just straight down where flashing and overhangs are designed to shed it.
- Salt air: Airborne salt accelerates the breakdown of caulk, fasteners, and factory coatings faster than it would inland, which means the protective seal at joints fails sooner than the manufacturer's testing environment might suggest.
- Long moss season: Moss and algae hold moisture directly against the siding surface for extended periods, especially on north-facing walls and anywhere shaded by trees — common throughout this area.
- Short drying windows: Even after a dry stretch, our humidity means surfaces don't fully dry out the way they would in a hot, arid climate — so any moisture that does get past the surface has less chance to evaporate before the next rain.
None of that means LP SmartSide will fail on every home. It means the margin for error is smaller here than in the climates where a lot of the product's reputation was built.
Installation Sensitivity Is the Real Risk
Here's the part that matters most: LP SmartSide's long-term performance is almost entirely dependent on installation details that are easy to get wrong and hard to inspect after the fact. Manufacturer warranties are explicit about this — cut edges must be field-sealed with the specified primer or sealant before installation, minimum clearances above rooflines, decks, and grade must be maintained, and caulking at joints has to be maintained on a schedule for the life of the siding.
The problem isn't that these requirements are unreasonable. It's that they depend on every installer, on every job, getting every detail right, and then on the homeowner keeping up with caulk maintenance indefinitely. We've seen how that plays out industry-wide: a rushed crew skips back-priming a cut end because it's going in a spot that "won't get wet," or caulk that should've been redone every few years gets missed because nobody flagged it. On a wood-based product, those small misses compound. On a non-combustible fiber cement product, the same misses are far more forgiving because the substrate itself doesn't absorb and swell the way wood does.
We install one product, on every job, with one crew that knows one installation standard cold. That consistency is worth more to us — and to the homeowner — than the lower material cost and faster install time LP SmartSide offers.
Cost and Maintenance Trade-Offs
| Factor | LP SmartSide | James Hardie Fiber Cement |
|---|---|---|
| Core material | Engineered wood strand, resin-treated | Cement, sand, and cellulose fiber — non-combustible |
| Moisture behavior | Resists moisture when sealed correctly; vulnerable at joints and cut edges if maintenance lapses | Dimensionally stable; doesn't swell or rot from moisture exposure |
| Upfront material cost | Generally lower | Generally higher |
| Ongoing maintenance | Periodic caulk inspection and renewal required at all joints and cut edges | Repainting on a longer cycle; no structural caulk dependency for moisture protection |
| Salt air / coastal exposure | Manufacturer treatment helps, but coatings and sealants degrade faster in salt air | Fiber cement itself doesn't corrode or absorb salt the way wood fiber can |
| Fire resistance | Combustible wood-based core | Non-combustible by composition |
| Warranty structure | Product warranty contingent on documented correct installation and maintenance | Strong transferable warranty on both substrate and factory finish |
The lower sticker price on LP SmartSide is real, and for some homeowners in some climates, that math works out fine over the life of the siding. Our judgment, specifically for homes in this part of Whatcom County, is that the maintenance burden and moisture risk shift more of the long-term cost onto the homeowner than the upfront savings justify.
Where LP SmartSide Genuinely Makes Sense
To be fair to the product: it holds paint well, it's lighter for crews to handle, it takes fasteners easily, and its impact resistance is decent for a wood-based product. On a home with wide overhangs, good grading, south or east exposure away from prevailing wind-driven rain, and an owner who's committed to inspecting and re-caulking on schedule, it can perform for a long time. If you're set on it, ask any installer for their specific field-sealing procedure on cut ends and their caulk maintenance schedule in writing — and hold them to it.
Why We Standardized on James Hardie
We made a deliberate decision to install one product across every job: James Hardie fiber cement siding. A few reasons drove that:
- Non-combustible core. Fiber cement doesn't burn, which matters increasingly in the Pacific Northwest as wildfire smoke seasons stretch longer even here.
- Dimensional stability. Hardie's cement-based composition doesn't swell, rot, or delaminate from moisture exposure the way a wood-fiber core can.
- ColorPlus factory finish. A baked-on finish applied under controlled conditions holds color and resists fading and chipping better than field-applied paint, and it's backed by its own warranty.
- Climate-engineered product lines. Hardie builds specific HZ formulations for different climate zones, including moisture-heavy regions like ours, rather than a single formulation expected to perform everywhere.
- Warranty strength. Hardie's transferable warranty coverage is substantial, and because the substrate itself is less installation-sensitive, there's less exposure for a warranty claim to get denied over a maintenance technicality.
Standardizing also means our crews install this one system constantly — every flashing detail, every joint treatment, every fastening pattern is second nature, not something relearned product to product. For a home sitting this close to Semiahmoo Bay, that consistency is exactly where we don't want to take chances.
Questions to Ask Any Contractor Before You Decide
- What siding material do they install as their standard, and why?
- If they install LP SmartSide, what's their written procedure for field-sealing cut edges and joints?
- Who is responsible for caulk maintenance after installation — and is there a documented schedule?
- What does the manufacturer warranty actually require of the homeowner to stay valid?
- How does the product perform specifically in coastal, high-moisture climates like Whatcom County, not just in general marketing claims?
If you're weighing siding options for a home in Semiahmoo or anywhere along Whatcom County's coastline, we're happy to walk through what we install, why, and what it would look like on your specific house. There's no pressure and no obligation — just a straight conversation and a free estimate.